In general, bell sounds and vibrations are used to receive a call in a portable terminal such as a mobile phone.
For vibrations, a small-sized vibration generation unit should be driven to transfer a driving force to a case of the device such that the entire terminal can vibrate.
A vibration generation unit, which is one of call reception units applied to a portable terminal such as a mobile phone, is a component for converting electrical energy into mechanical vibrations using a principle of generating an electromagnetic force, and is mounted to the portable terminal for a call alarm without using sounds.
The vibration generation unit is widely used for the purpose of informing a user of reception of a call in a portable terminal, and has recently been mounted to a game unit to inform the user of a process state of a game or mounted to a touch phone and the like to be used for the purpose of allowing the user to feel that a key is touched.
As the portable terminal market is rapidly expanding and various functions are being added to the portable terminal, a need for development of a product of a new structure which can improve disadvantages of an existing vibration generation units and remarkably improve quality is rising in a situation requiring miniaturization and high quality of components of the portable terminal.
A vibration generation unit mounted to a portable terminal according to the related art basically primarily uses a vibrometer, and a weight body is attached to a resilient body such as a coil spring and a coil for vibrating the weight body is provided.
If a current is applied to the coil, the weight body vibrates according to predetermined frequency response characteristics due to the resilient coefficients of the weight body and the resilient body.
As described above, the recently released portable terminal outputs sounds or vibrations in response to a touch input of the user to provide a function of providing a feedback corresponding to an input for the user.
In particular, for the portable terminal employing a haptic technology, studies on vibration generation units for generating various types of vibrations to provide various haptic feedbacks in response to various inputs are being conducted, and Korean Patent Application Publication No. 10-2008-0107506 discloses such a vibration generation unit.
However, the vibration generation unit according to the related art generates a vertical driving force of a weight body with a Lorentz's force generated between a coil and a fixed magnet, but it has been difficult to show good characteristics in the strengths of vibrations and frequency bands of vibrations due to a limit in the vibration generation unit due to the Lorentz's force.
In addition, because the vibration generation unit according to the related art has a structure in which a permanent magnet included in a weight body moves in a fixed coil, a possibility of collision of a coil and a permanent magnet is high, causing noise and short-circuiting the coil, and it is difficult to dispose the permanent magnet in the coil such that a predetermined interval is provided between the permanent magnet and the coil when the product is assembled.